An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 68 Search : bit
aberration orbit
  مدار ِ بیراهش   
madâr-e birâheš

Fr.: orbite d'aberration   

The apparent path described by a star on the → celestial sphere due → annual aberration. A star at the → ecliptic pole is seen to move around a circle of angular radius about 20".50, once a year. A star on the → ecliptic oscillates to and fro along a line of angular half-length 20".50. At an intermediate → celestial latitude, β, the aberration orbit is an ellipse, with semi-major axis 20".50 and semi-minor axis (20".50) sin β.

aberration; → orbit.

arbitrary
  کامسر   
kâmsar

Fr.: arbitraire   

1) Based on individual will or choice rather than by reason or necessity.
2) Math.: Undetermined; of unspecified value. → arbitrary constant.

M.E., from O.Fr. arbitraire or directly from L. arbitrarius "depending on the will, uncertain," from → ad- "to" + baetere "to come, go."

Kâmsar, literally "at one's will," from kâm "desire, wish; cause, reason," → despite, + sar "person, individual," originally "→ head."

arbitrary constant
  پایای ِ کامسر   
pâyâ-ye kâmsar

Fr.: constante arbitraire   

A constant quantity in → equations which takes various values but which remains unaffected by the changes in the values of the → variables of the equation. Most → differential equations have more than one → solution. In general, the number of arbitrary constants of an ordinary differential equation is given by the → order of the highest → derivative.

arbitrary; → constant.

binary digit (bit)
  رقم ِ درین، ~ دودو‌یی، بیت   
raqam-e dorin, ~ dodoi, bit

Fr.: chiffre binaire   

Either of the digits 0 or 1, used in the → binary number system.

binary, → digit.

bit
  بیت، رقم ِ درین   
bit, raqam-e dorin

Fr.: bit   

A contraction of → binary digit, either 0 or 1.

Bit, from binary + digit

bound orbit
  مدار ِ بندیده   
madâr-e bandidé

Fr.: orbite liée   

The orbit described by an object around a central gravitational force in a system whose total energy is negative. An elliptical orbit.

Bound, p.p. of → bind; → orbit.

Madâr, → orbit; bandidé, p.p. of bandidan, → bind.

circular orbit
  مدار ِ دایره‌ای، ~ پرهونی   
madâr-e dâyere-yi, ~ parhuni

Fr.: orbite circulaire   

The path of a object in → circular motion.

circular; → orbit.

circumstellar habitable zone
  زنار ِ زیست پذیر ِ پیراستاره‌ای   
zonâr-e zistpazir-e pirâsetâreyi

Fr.: zone habitable circumstellaire   

A zone around a star within which a planet can have temperatures that permit liquid water, depending on the luminosity of the star and the distance of the planet from it.

circumstellar; → habitable zone.

co-orbital
  هم‌مدار   
ham-madâr

Fr.: co-orbital   

Of or relating to two or more celestial bodies that share, or almost share, the same orbit.

co-; → orbital.

co-orbital motion
  جنبش ِ هم‌مداری   
jonbeš-e ham-madâri

Fr.: mouvement co-orbital   

The motion of two or more bodies around the Sun on different orbits when it takes them the same amount of time to complete one revolution. There are three possible types of co-orbital motions of a small body associated with a planet: → tadpole orbits, → horseshoe orbits, and → quasi-satellite orbits.

co-orbital; → motion.

co-orbital satellite
  ماهواره‌ی ِ هم‌مدار، بنده‌وار ِ ~   
mâhvâre-ye ham-madâr, bandevâr-e ~

Fr.: satellite co-orbital   

Any of satellites which either share the same orbit or which occupy immediately adjacent orbits that change periodically as the satellites approach one another (Ellis et al., 2007, Planetary Ring Systems, Springer).

co-orbital; → satellite.

co-orbiting
  هم‌مداری؛ هم‌مدار   
ham-madâri; ham-madâr

Fr.: co-orbitage; c-orbitant, co-orbiteur   

The action or quality of a → co-orbiting asteroid.

From co- "together," → com- + → orbit + → -ing.

From ham- "together," → com- + madârorbit + -i noun suffix.

co-orbiting asteroid
  سیارک ِ هم‌مدار   
sayyârak-e ham-madâr

Fr.: astéroïde co-orbiteur   

An asteroid having a → co-orbital motion.

co-orbiting; → asteroid.

cometary orbit
  مدار ِ دنباله‌دار   
madâr-e donbâledâr

Fr.: orbite de comète   

The → path followed by a → comet in the → solar system around the → Sun. Most cometary orbits appear to be → elliptical, or in some cases → parabolic. The orbits of → short-period comets are elliptical, carrying them out to a region lying from → Jupiter to beyond the orbit of → Neptune. Those of → long-period comets are very elliptical. The orbits may be strongly influenced if they pass near the Jovian planets, particularly Jupiter itself. The cometary orbits are also influenced to some degree by gases shooting out of comets, so their orbits are primarily but not completely determined by gravity. Newton (1644-1727) was the first to compute a cometary orbit. He found that the comet of 1680 was following a parabolic orbit around the Sun. Edmond Halley (1656-1742), following the methods of Newton, computed the → orbital elements of 24 comets. He realized that the comets of 1531, 1607 and 1682 had very similar elements and postulated that they were in fact the same object, orbiting an elongated ellipse. He predicted the next return to occur in 1758 or early 1759. The return of what is now called Halley's comet was observed after his death, This first observation of a "predicted" comet is manifestly one of the major successes of → celestial mechanics.

cometary; → orbit.

commensurate orbits
  مدارها‌ی ِ هم مسا   
madârhâ-ye hammasâ

Fr.: orbites commensurables   

Of two bodies orbiting around a common barycenter, when the orbital period of one is an exact fraction, for example one-half or two-thirds, of the other.

commensurate; → orbit.

de-orbit
  وامداریدن   
vâmadâridan

Fr.: désorbiter   

To cause a spacecraft to leave its operational orbit to enter a descent phase or to change course.

From → de- + → orbit.

de-orbiting
  وامدارش   
vâmadâreš

Fr.: désorbitage   

Of a spacecraft, the act or process of departing from an operational orbit. → de-orbit.

Noun form of → de-orbit.

elements of the orbit
  بن‌پارهای ِ مدار، عنصرهای ~   
bonpârhâ-ye madâr, onsorhâ-ye ~ (#)

Fr.: éléments orbitaux   

orbital element.

element; → orbit.

elongated orbit
  مدار ِ کشیده، ~ درازیده   
madâr-e derâzidé, ~ kašidé

Fr.: orbite allongée   

An → elliptical orbit with a high → eccentricity.

elongated; → orbit.

Galactic habitable zone
  زنار ِ زیست‌پذیر ِ کهکشان   
zonâr-e zistpazir-e kahkešân

Fr.: zone habitable galactique   

A region of the Galaxy whose boundaries are set by its calm and safe environment and access to the chemical materials necessary for building terrestrial planets similar to the Earth. → circumstellar habitable zone; → habitable zone.

galactic, → habitable; → zone.

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